ISL5571A

The ISL5571A is a solid state device designed to replace the  electromechanical relay used on Subscriber Line Cards. The device contains two Line Break MOSFET switches, one Ring Return MOSFET switch and one Ring Access SCR switch.The ISL5571A is pin-for-pin compatible with the Lucent
L7581AAE LCAS and Clare CPCL7581A Products.

Improvements include: line break switches rON match (0.5Ω Max) higher dV/dt sensitivity (5000V/µs), protection SCR hold current set to 110mA.

The line break MOSFETs have very low on resistance (<16.0Ω Typ) and Ron match (<0.05Ω Typ, 0.5Ω Max) and a blocking voltage >330V. The Ring Return MOSFET has a typical Ron of 50Ω and a blocking voltage >330V. The Ringing Access switch is implemented with a SCR device
with a blocking voltage >480V. The SCR switch inherently offers low EMI connect and disconnect circuitry. All control I/Os use TTL thresholds making the device compatible with 3V logic.

The ISL5571A also includes on-chip protection in the form of an over-voltage clamping circuit, current-limited MOSFET switches, and thermal shutdown circuitry. The over-voltage clamping circuit consists of a diode bridge and SCR.